#include<iostream>
#include<cstdlib>
#include<unistd.h>
#include<sys/types.h>
#include<sys/wait.h>
#include<string.h>

//让父进程读取，子进程写入
int main()
{
    //1.创建管道
    int fds[2] = {0};
    int n = pipe(fds);//输出型参数
    if(n != 0)
    {
        //创建失败
        std::cerr<<"pipe error"<<std::endl;
        return 1;
    }

    //2.创建子进程
    pid_t id = fork();
    if(id < 0)
    {
        std::cerr <<"fork error"<<std::endl;
        return 2;
    }
    else if(id == 0)
    {
        //子进程
        //3.关闭不需要的fd，子进程关闭读read
        ::close(fds[0]);//::表示使用全局的方法，这里表示是系统函数

        //发数据
        int cnt=1;
        int total = 0;
        while(true)
        {
            std::string message = "w";
            // message +=std::to_string(getpid());
            // message +=",";
            // message += std::to_string(cnt);

            //fds[1]
            total += ::write(fds[1],message.c_str(),message.size());
            cnt++;
            std::cout<<"total:"<<total<<std::endl;
            sleep(2);

            // break;
        }
        exit(0);
    }
    else
    {
        //父进程
        //3.关闭不需要的fd,父进程关闭写write
        ::close(fds[1]);

        //接受数据
        char buffer[1024];
        while(true)
        {
            ssize_t n = ::read(fds[0],buffer,1024);
            if(n > 0)
            {
                buffer[n] = 0;
                std::cout<<"child->father,message:"<<buffer<<std::endl;
            }
            else if(n == 0)
            {
                //如果写端关闭
                //读端读完管道内的数据，再读取的时候，就会读取到返回值0，表示对端关闭，也表示读到文件结尾
                std::cout<<"n:"<<n<<std::endl;
                std::cout<<"father wait child success: "<<std::endl;
                break;
            }
            close(fds[0]);
            break;
            std::cout<<std::endl;
        }

        //等待子进程
        int status = 0;
        pid_t rid = waitpid(id,&status,0);
        std::cout<<"father wait child success:"<<rid<<"exit code:"<<((status<<8)&0xFF)<<",exit sig:"<<(status & 0x7F)<<std::endl;
    }
    return 0;
}